The question of how cells form long asymmetric processes will be investigated in Astrocytes and in Sf9 cells infected with baculovirus carrying cDNAs encoding various cytoskeletal proteins. The experiments will look at the role of the myosin light chain, myosin light chain kinase, destrin and protein phosphatases in mediation of astrocytic relaxation and stellation. The role of the actin-rich distal tip of the process in regulation of microtubule assembly in the process shaft will be examined by video microscopy and the microinjection of labeled tubulin and actin. It is proposed that nitric oxide may be an important messenger in the neuronal-induced stellation of astrocytes and in the autoregulation of astrocytic shape which may occur in injury. The necessity for GFAP in stabilizing the astrocytic process will be evaluated after anti-sense oligonucleotide down regulation of GFAP levels. The Sf9 cells will be used as a model system with certain features of the nerve axon to investigate the interactions between microtubule accessory proteins and the neuronal intermediate filaments. Proteins which will be studied include HMW tau, LMW tau, various domains of the tau molecule, MAP1b and its light chain, peripherin, NF-L, NF-M and NF-H.